P.6 Low

Vaillant P.6 Fault Code

Also written as P6 — same fault.

The Vaillant P.6 fault code means: your boiler is currently running a maintenance program to help fill or drain the system, meaning it has temporarily paused its normal heating and hot water functions.. It appears on 14 Vaillant models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Filling/draining programme: The preference changeover valve moves to the centre position. The burners and pump are switched off.

What causes the Vaillant P.6 fault?

This code appears when the boiler's internal software has been manually or automatically put into a specialized service mode for maintenance. It physically shifts the internal valves to a central position to allow water to flow freely through the system for filling or draining. Because the boiler is focusing entirely on moving water, it temporarily stops the burner from firing to prevent overheating.

Typical repair cost £0-80 (including labour)

DIY fix possible

Wait approximately 15 minutes for the program to complete automaticallyEnsure the blue filling loop handles under the boiler are fully closedRestart the boiler using the power button if the code persists for over 30 minutes

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Vaillant models that show the P.6 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vaillant P.6 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026